You can set all non-graded items to count as a zero if you wish by removing the tick next to the "Aggregate only non-empty grades" checkbox in your gradebook. This will determine how you will deal with blank assignments/zeros.
Do Not Aggregate Only Non-Empty Grades (Recommended): Leave the "Aggregate only non-empty grades" check box unchecked if you want all grade fields to be taken into consideration until the end of the course. All incomplete assignments will register as a zero, and the running course total will be a percentage out of the whole (i.e. the student will see 40/400). This will require you to educate your students about the process of being graded in an online environment. Explain that this is a cumulative grade, and it will build toward the final course grade as they progress through the course.
Aggregate Only Non-Empty Grades: Check the "Aggregate only non-empty grades" check box so that blank grades are NOT calculated as zeros. All incomplete coursework will be ignored for scoring. This will require you to enter a zero for missing, incomplete, or late work if you want the zero to factor. If you don't enter a zero in work that has yet to be completed, the running course total can be misleading (i.e. it will appear that a student has 40/40 even though there are 400 points in a course).
An empty grade is simply a missing gradebook entry, and could mean different things. For example, it could signal an unsubmitted assignment, an assignment submission not yet graded by the teacher, or a grade that was manually deleted by the gradebook administrator. Caution in interpreting these "empty grades" is thus advised.
